A long-standing mystery in the study of glaciers was recently — and serendipitously-solved by a team led by University of Hawai’i at Mānoa astrobiologist and earth scientist Eric Gaidos. Their findings were published this week in the journal Geophysical Research Letters.
The mystery involves floods or “jokulhlaups” that emerge suddenly and unpredictably from glaciers or ice caps like those in Iceland where volcanic heat melts the ice and water accumulates in lakes underneath the glaciers. Scientists have long studied the development of these floods, which are some of the largest on Earth.
“These floods may affect the motion of some glaciers and are a significant hazard in Iceland,” said Gaidos, professor at the UH Mānoa School of Ocean and Earth Science and Technology (SOEST). “But the mechanism and timing of the initiation of these floods has not been understood.”
Then, in June 2015, an unexpected series of events revealed how these floods start.
That summer, Gaidos and colleagues drilled a hole to one of the Icelandic lakes to study its microbial life. While collecting samples through the borehole, the team noticed a downwards current, like a bathtub drain, in the hole.
“The flow was so strong we nearly lost our sensors and sampling equipment into the hole,” said Gaidos. “We surmised that we had accidentally connected a water mass inside the glacier to the lake beneath. That water mass was rapidly draining into the lake.”
A few days later, after the team had left the glacier, the lake drained in a flood. Fortunately, the flood was small and Icelanders have an elaborate early-warning system on their rivers so no people were hurt, nor infrastructure damaged in this event, Gaidos assured.
The researchers used a computer model of the draining of the flow through the hole , and its effect on the lake, to show that this could have triggered the flood.
“We discovered that the glacier can contain smaller bodies of water above the lakes fed by summer melting,” said Gaidos. “If this water body is hydraulically connected to the lake then the pressure in the lake rises and that allows water to start draining out underneath the glacier.”
While the team made an artificial connection to the lake in 2015, natural connections can form when water from rain or melting snow accumulates in crevasses and the pressure eventually forces a crack through the glacier to the lake. This discovery provides a new understanding of how these floods can start and how this depends on weather and the season.
Collaborators in Iceland are continuing to research this phenomenon using radio echo-sounding to search for water bodies within the ice, as well as study the larger lake below it.
Fossilized jaw bone fragments of a rat-like creature found at the Petrified Forest National Park in Arizona last year by a Virginia Tech College of Science Ph.D. candidate are in fact a newly discovered 220-million-year-old species of cynodont or stem-mammal, a precursor of modern-day mammals.
The finding of this new species, Kataigidodon venetus, has been published today in the journal Biology Letters by lead author Ben Kligman, a doctoral student in the Department of Geosciences.
“This discovery sheds light on the geography and environment during the early evolution of mammals,” Kligman said. “It also adds to evidence that humid climates played an important role in the early evolution of mammals and their closest relatives. Kataigidodon was living alongside dinosauromorphs and possibly early dinosaurs related to Coelophysis — a small bipedal predator — and Kataigidodon was possibly prey of these early dinosaurs and other predators like crocodylomorphs, small coyote-like quadrupedal predators related to living crocodiles.”
Kligman added that finding a fossil that is part of Cynodontia, which includes close cousins of mammals, such as Kataigidodon, as well as true mammals, from Triassic rocks is an extremely rare event in North America. Prior to Kligman’s discovery, the only other unambiguous cynodont fossil from the Late Triassic of western North America was the 1990 discovery of a braincase of Adelobasileus cromptoni in Texas. Note that 220 million years ago, modern day Arizona and Texas were located close to the equator, near the center of the supercontinent Pangaea. Kataigidodon would have been living in a lush tropical forest ecosystem.
Kligman made the discovery while working as a seasonal paleontologist at Petrified Forest National Park in 2019. The two fossil lower jaws of Kataigidodon were found in the Upper Triassic Chinle Formation. Because only the lower jaws were discovered and are quite small — half an inch, the size of a medium grain of rice — Kligman only has a semi-picture of how the creature looked, roughly 3.5 inches in total body size, minus the tail.
Along with the jawbone fossils, Kligman found incisor, canine, and complex-postcanine teeth, similar to modern day mammals. Given the pointed shape of its teeth and small body size, it likely fed on a diet of insects, Kligman added. (Why are jaw fossils commonly found, even among small specimens? According to Kligman, the fossil record is “biased” toward only preserving the largest and most robust bones in a skeleton. The other smaller or more fragile bones — ribs, arms, feet — disappear.)
Kligman carried out field work, specimen preparation, CT scanning, conception, and design of the studyand drafting of the manuscript. He added that he and his collaborators only discovered the fossils were of a new species after reviewing the CT scan dataset of the jaws and comparing it to other related species.
“It likely would have looked like a small rat or mouse. If you were to see it in person you would think it is a mammal,” Kligman added. Does it have fur? Kligman and the researchers he worked with to identify and name the creature actually don’t know. “Triassic cynodonts have not been found from geological settings which could preserve fur if it was there, but later nonmammalian cynodonts from the Jurassic had fur, so scientists assume that Triassic ones did also.”
The name Kataigidodon venetus derives from the Greek words for thunderstorm, “kataigidos,” and tooth, “odon,” and the Latin word for blue, “venetus,” all referring to the discovery location of Thunderstorm Ridge, and the blue color of the rocks at this site. Kligman didn’t name the creature, though. That task fell to Hans Dieter-Sues, coauthor and curator of vertebrate paleontology at the Smithsonian National Museum.
Additional collaborators include Adam Marsh, park paleontologist at Petrified Forest National Park, who found the jaw fossils with Kligman, and Christian Sidor, an associate professor at the University of Washington’s Department of Biology. The research was funded by the Petrified Forest Museum Association, the Friends of Petrified Forest National Park, and the Virginia Tech Department of Geosciences.
“This study exemplifies the idea that what we collect determines what we can say,” said Michelle Stocker, an assistant professor of geosciences and Kligman’s doctoral advisor. “Our hypotheses and interpretations of past life on Earth depend on the actual fossil materials that we have, and if our search images for finding fossils only focuses on large-bodied animals, we will miss those important small specimens that are key for understanding the diversification of many groups.”
With Kataigidodon being only the second other unambiguous cynodont fossil from the Late Triassic found in western North America, could there be more new species out there waiting to be found?
Kligman said most likely. “We have preliminary evidence that more species of cynodonts are present in the same site as Kataigidodon, but we are hoping to find better fossils of them,” he added.
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